Washington, Sept 27 : Less than a month after the Mumbai attacks, Pakistan's ISI chief Lt Gen Ahmed Shuja Pasha had admitted before the CIA that the terror strikes had ISI links but claimed it was not an "authorised" operation and carried out by "rogue" elements, according to a new book.

However, the Central Intelligence Agency (CIA) later received reliable intelligence that the ISI was directly involved in the training for Mumbai, says the book entitled 'Obama's War' written by investigative American journalist Bob Woodward.

According to the book, the then President George W Bush during his meetings with his top aides had said that the terrorist attack on Mumbai was just like 9/11.

"President Bush called his national security team into the Oval Office as Mumbai sorted through the blood and rubble. You guys get planning and do what you have to do to prevent a war between Pakistan and India, Bush told his aides. The last thing we need right now is a war between two nuclear-power states," Woodward says in his book which hit the stands today.

Giving an insight into the thinking and actions of the Bush Administration during and immediately after the Mumbai attacks, Woodward writes that an "upset Bush asked his aides about contingency plans for dealing with Pakistan," given his policy of "zero tolerance" for terrorists and their enablers.

"This is like 9/11, he (Bush) said," Woodward wrote.

"The United States military did not have 'war' plans for an invasion of Pakistan. Instead, it had and continues to have one of the most sensitive and secret of all military contingencies, what military officials call a 'retribution' plan in the event of another 9/11-like attack on the US by terrorists based in Pakistan," the book says.

Under this plan, the US would bomb or attack every known al-Qaeda compound or training camp in the US intelligence database. "Some locations might be outdated, but there would be no concern, under the plan, for who might be living there now. The attribution plan called for a brutal punishing attack on at least 150 or more associated camps," Woodward says.

According to Woodward, within 48 hours of the Mumbai attack, the then CIA Director Mike Hayden contacted Pakistan Ambassador to the US, Hussain Haqqani.

"CIA intelligence showed no direct ISI links, Hayden told him. These are former people who are no longer employees of the Pakistani government," he wrote.

"Bush informed the Indians himself. He called Indian Prime Minister Manmohan Singh, with whom he had a strong personal relationship. My intelligence shows that the new Pakistani government is not involved, Bush said. It looked like a war had been averted for the moment," Woodward writes.

"In a call to Lieutenant General Ahmed Shuja Pasha, the head of the Pakistani ISI, Hayden said, "We've got to get to the bottom of this. This is a big deal'," the book says.

He urged Pasha to come clean and disclose all.

On the day after Christmas, Pasha flew to the United States, where he briefed Hayden at CIA headquarters, the author writes.

"Pasha admitted that the planners of the Mumbai attacks at least two retired Pakistani Army officers had ISI links, but this had not been an authorised ISI operation. It was rogue. There may have been people associated with my organisation who were associated with this," Pasha said.

"That's different from authority, direction and control," Pasha is quoted as saying by Woodward.

According to Woodward, Pasha provided details that fit with the picture developed by US intelligence.

"Hayden told Bush he was convinced it was not an official Pakistani-sponsored attack, but it highlighted the problem of the sanctuaries in Pakistan. The ease of the planning and execution, the low cost, and the alarming sophistication of the communications system that LeT had used were all troubling," he said.

The author says that the Mumbai terrorists spoke with handlers back in Pakistan with satellite phones that went through a Voice over Internet Protocol (VoIP) phone service in New Jersey, making the calls difficult, if not impossible to trace and routed them in a way that also concealed the locations of those talking.

"The FBI was horrified by the low-cost, high-tech operation that had paralysed Mumbai. American cities were just as vulnerable. A senior FBI official responsible for thwarting similar attacks in the United States said, Mumbai changed everything," the book says.

In his book, Woodward writes that the open secret is that LeT was created and continues to be funded by the Pakistani ISI.

"The intelligence branch of the Pakistani military uses LeT to inflict pain and hardship on India, according to US intelligence. These gunmen had, quite possibly, committed an act of war," Woodward says. PTI